The present invention proposes a marble or stone slab polishing machine to polish slabs made from stone, marble or the like. More particularly, the present machine is to polish the borders of slabs. The main feature of this machine is the presence of a tools holding head pivoted round a fulcrum.
More precisely, the machine according to this invention comprises a slab supporting part in which the slabs are fed on a horizontal band disposed in the front of the machine. The borders of the slabs are worked by polishing tools of heads arranged on a unit that is rotated angularly and is mounted on fulcrum supports.
In comparison with the prior art the present machine offers many important advantages. Concerning the practicalness, the working processes are simpler and there is less wear and tear in the movable parts. Concerning the construction, the present machine avoids the utilization of the conventional supporting units needed to permit an angular movement along a curved path. As is known, the said supporting units are complex and costly.
As is known, in the sector of the working of stone and marble materials several machines are utilized to perform different tasks. The main tasks are the cutting, shaping and polishing of the pieces.
Specifically, some of the said machines are utilized to shape and polish the borders of slabs made of granite, marble, stone and glazed materials.
The said machines are generally called border polishers and permit to polish the borders of slabs, for instance when it is necessary to obtain kitchen planes and shelves or surfaces provided with a toroidal border. The machine is therefore equipped with components that permit the raw slab to be subjected to the roughing and polishing operations so as to obtain a perfectly polished slab border.
The conventional slab border polishing machines are provided with a horizontal supporting plane provided with a conveyor belt. The marble or stone slab to be worked is placed on the said conveyor belt so that the slab advances progressively.
In the proximity of the rear of the machine and more precisely, beyond the conveyor belt there is a working unit provided with working and polishing tools. As the slab advances with a linear movement at a constant speed, the said tools work and polish the slab.
The working and polishing tools are represented by a series of heads. Each head is provided with a grinder. The heads are arranged side by side and in parallel succession on supports that permit the heads to be displaced angularly in respect of the working centre of the slab border.
The head supports are normally utilized in the border polishing machines and are represented by arc guides disposed on the two ends of a bar. The arc guides support suitable sliding blocks to permit an angular sliding of the bar itself. Both the sliding blocks and the arc guides are moved through independent motorized actuating systems.
The prior art discloses moving systems based on a series of connecting rods that permit the head unit to rotate like a four-bar linkage. However, in this case, the constructive structure is too complex.
It is evident that the said actuating head system is complex and expensive and involves many difficulties as concerns the construction and the operation of the machine, the costs of such machines and the costs of their operation being too high. In addition, there is a great wear and tear of the moving components.